Yet again another SES light on 2001 Bonnie
 

I am getting code P0420

possible causes cataltic converter failure.
Engine misfire or running condition
Large Vacuum leak
Engine oil leak into exhaust-valve guide
Piston Rings

What do you all think.

It's been 1 ses after another with this car, but I am determined to get it fixed!

check your vacuum lines with carb cleaner and inspect them thoroghly by hand also spray around the base of the supercharger and fuel injectors and see if the idle changes

where are the vacuum lines located exactly?

Take a look here. https://www.gmforum.com/showthread.p...86#post1390979 This code can come from a exhaust leak. With all the codes your getting I'm starting to think you have leaks. Vacuum and exhaust. Your going to have to go over everything.

https://www.gmforum.com/specifications-general-information-132/vacuum-lines-sensors-278867/

What brand of cataltic converter should I look into getting if that is the problem. aftermarket are about 170 bucks. Is there a certain brand better then another and also the best place to get one.

Unless you hear rattling inside the cat, it's probably OK. Check for a exhaust leak. This includes the exhaust gaskets. If you get a can of seafoam and then suck about 1/3 of that can up threw one of the smaller vacuum lines, then shut the engine off and let it sit for about 20 minutes. Then start the engine. It will smoke a lot. Have a flashlight handy and watch real close for any leaking smoke.

I thought you were also chasing down an O2 sensor issue? Did that ever get replaced?

I'm leaning towards the O2 sensor as well as some vacuum issues.

No I never replaced the o2 sensor yet. I am going to take it back to midas who did the weld job on my exhaust to see if they will warranty it and maybe look for another leak for me.

The guy at midas told me to bring it in and they would do test on the cat coverter and see if it actually bad for free. But he does not recommend using seafoam, but I tend to believe you guys before him. He thinks the P0420 code is my cat converter but I will take it to him today and we will see.

Well while driving the car back to midas to look at the ses light it goes off... So the light went off and I decided not to go to midas. What would cause the light to just go off now. Obviously it is fixed now or the computer thinks it is ok now. I really don't think it is my cat for the fact no rattling or noise from it. If it is the o2 sensor maybe it is intermittent. Well just wanted to see what your thoughts are on why the light would just go off on it's own.

DTC's often reset after XX amount of times where a set parameter was not seen. Though you may think the problem is fixed once a DTC's presents itself, its just a matter of time before it comes back.

Your absolutely right it just came back on...so to midas I go.

GM seems to use three different things.
1. Resets when the car is restarted and problem doesn't appear with initial tests
2. 3 consecutive drive cycles
3. 50 Drive cycles.

You probably hit the 3 test cycles and it went off. Yet the problem still exists.

Ok sorry about the long time no post...but been having alot of issues with my bonne...it is basically falling apart at 160K now. I ordered a new cat for it and midas will put it on for 75-100 depending on what needs to be welded, because now at low idle on the highway my car's engine is shutting off, I assume because the cat or exhaust is getting to hot or clogging. So I put it in park and restart and it comes right back on. But I know it is because of the exhaust and/or cat issue. I bought some seafoam to put in, but need some advise where is the best place to put it in the gas tank or the oil tank? It states on the bottle it can do different things depending on where you put it...I think to get the most benefit from it I would need to put in the oil crank. Please advise on where it should go.

Thanks Guys!

Suck 1/3 can in to a vacuum line then shut off the engine for about 20 mins, and the other 2/3 in the fuel tank. Change the oil shortly after doing this.

Can you advise me on how to go about putting it through the vacuum lines? Is it hard or easy? Any details would be helpful..Thanks Dan

That should be covered in tech info.

I've searched for it to no avail...can someone please post a link to where the PCV valve is on a 2001 bonneville SSEI..

Thanks,

Top of the supercharger, rear near the throttle body. It's a black oval cover that says PCV on it.

So I just remove those 2 bolts and I can put the seafoam in that hole once I take out the spring, or do I need to take out the PCV Valve? Also when I intake the seafoam does the engine need to be running or not?

No, don't pour the seafoam there. Pull one of the smaller vacuum lines between the throttle body and the supercharger. Like the three on top. Don't choose the brake booster, choose a smaller line.

Too dark to mess with this tonight I just poured half the bottle in the gas tank and half in the oil crankcase and drove it around the block, I will get another can and do the vacuum line sometime tomorrow. Why was I shown the PCV valve when thats not where I needed to put it? I pull a small hose off between the supercharger and the throttle and use the small hose line to intake the seafoam..I wish there was a step by step on how to do this properly, I still don't know if I need the car to be running when I do this or not.

This is stated on their FAQ on their website so I am warry of doing it myself not knowing a damn thing about my induction system

These special application procedures (called the “induction application method”) are described in other sections of this website, and can be performed by any mechanically competent individual having detailed knowledge of their engine’s fuel and induction systems. However, relying on your professional mechanic to perform these procedures is the safer choice. But for the average automobile owner, routinely adding Sea Foam Motor Treatment to your fuel tank according to the instructions will give you the same benefits as the induction method, improving performance and prolonging the life of your engine – it just takes a little longer to see the results.

Because you asked where is the PCV valve.

I've given you a step by step. Start the engine, pull a small vacuum line, suck up 1/3 can, shut off engine, let sit for 20 mins, start engine.

Thanks Dan didn't mean to be a PAIN, but I am a newb when it comes to the engine. I appoligize for being so new to this, but please bear with me while I am learning. I won't bother you again with trivial things...

We all need to learn at some point.

hey stinger! hey man get a list of things together you would like done. i will be down there in august and will help ya do what you need to do

Have fun

Cool beans, that would be nice to have 1 gearhead in my area to be able to help with things....I don't know anyone in this area with a bonneville that works on their cars. So I will get a list...let me know more info, and I can let you know how to find me :)

sent ya a PM with my info just let me know